From fa44cef27b0f7fd8438c249f2f405816069c339e Mon Sep 17 00:00:00 2001
From: Sylvain Rochet <gradator@gradator.net>
Date: Fri, 1 May 2015 00:49:19 +0200
Subject: [PATCH] PPP, L2TP, added configurable L2TP MRU using opt.h

---
 src/include/lwip/opt.h   | 11 +++++++++++
 src/netif/ppp/pppol2tp.c |  4 ++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/include/lwip/opt.h b/src/include/lwip/opt.h
index 5216e50e..9af4ad9d 100644
--- a/src/include/lwip/opt.h
+++ b/src/include/lwip/opt.h
@@ -2316,6 +2316,17 @@
 #define PPP_MINMRU                      128      /* No MRUs below this */
 #endif
 
+/**
+ * Default MTU and MRU for L2TP
+ * Default = 1500 - PPPoE(6) - PPP Protocol(2) - IPv4 header(20) - UDP Header(8)
+ * - L2TP Header(6) - HDLC Header(2) - PPP Protocol(2) - MPPE Header(2) - PPP Protocol(2)
+ */
+#if PPPOL2TP_SUPPORT
+#ifndef PPPOL2TP_DEFMRU
+#define PPPOL2TP_DEFMRU                 1450
+#endif
+#endif /* PPPOL2TP_SUPPORT */
+
 #ifndef MAXNAMELEN
 #define MAXNAMELEN                      256     /* max length of hostname or name for auth */
 #endif
diff --git a/src/netif/ppp/pppol2tp.c b/src/netif/ppp/pppol2tp.c
index 1514134b..7e8fbafe 100644
--- a/src/netif/ppp/pppol2tp.c
+++ b/src/netif/ppp/pppol2tp.c
@@ -285,13 +285,13 @@ static err_t pppol2tp_connect(ppp_pcb *ppp, void *ctx) {
   ppp_clear(ppp);
 
   lcp_wo = &ppp->lcp_wantoptions;
-  lcp_wo->mru = 1500; /* FIXME: MTU depends if we support IP fragmentation or not */
+  lcp_wo->mru = PPPOL2TP_DEFMRU;
   lcp_wo->neg_asyncmap = 0;
   lcp_wo->neg_pcompression = 0;
   lcp_wo->neg_accompression = 0;
 
   lcp_ao = &ppp->lcp_allowoptions;
-  lcp_ao->mru = 1500; /* FIXME: MTU depends if we support IP fragmentation or not */
+  lcp_ao->mru = PPPOL2TP_DEFMRU;
   lcp_ao->neg_asyncmap = 0;
   lcp_ao->neg_pcompression = 0;
   lcp_ao->neg_accompression = 0;